Stress May Affect Memory and Brain Size

Men and women who had high blood levels of cortisol, the so-called stress hormone, performed worse on tests of memory than those with normal cortisol levels. They also had smaller brains volumes, which has been linked to an increased risk of dementia later in life.

“Cortisol affects many different functions, so it is important to fully investigate how high levels of the hormone may affect the brain,” said study author Dr. Justin B. Echouffo-Tcheugui of Harvard Medical School.

Cortisol, produced by the adrenal glands, helps the body respond to stress. It helps to control inflammation, blood sugar and blood pressure levels, among other body functions. Persistently high cortisol levels are a sign of chronic stress.

For the study, researchers looked at 2,231 men and women, most in their 40s or 50s. All were part of a larger study and free of dementia.

Study participants were given tests of memory and thinking skills at the start of the study, and again eight years later.

Doctors also collected blood tests to measure cortisol levels, and most had MRI brain scans to assess brain size.

Participants were divided into three groups: low, middle and high cortisol levels.

Those with the highest cortisol levels, a sign of stress, had lower scores on tests of memory and thinking skills than those with normal levels of cortisol. They also had slightly smaller brain volumes. No links were found between low cortisol levels and memory or brain size.

The researchers controlled for smoking, high blood pressure, blood vessel disease and other factors that can impact brain health. Still, the ties between cortisol levels and memory impairment and brain size persisted. The findings were published in Neurology.

“Our research detected memory loss and brain shrinkage in middle-aged people before symptoms started to show,” said Dr. Echouffo-Tcheugui. As a result, “It’s important for people to find ways to reduce stress, such as getting enough sleep, engaging in moderate exercise, incorporating relaxation techniques into their daily lives, or asking their doctor about their cortisol levels and taking a cortisol-reducing medication if needed.”

By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.